The medical and health care profession has administered therapeutic radiation treatments to animals and human patients to reduce, slow down or affect the growth of or to achieve the destruction of various cancers or tumors affecting such animals or patients. A recognition of the medical health profession to the lack of efficacy of radiation on certain tumors has arisen. Specifically, species of tumors exist wherein due to rapid growth rate or other characteristics, an oxygen depleted or hypoxic zone exists within the tumor. Such hypoxic cells are not amenable to traditional radiation therapy without incurring such severe conditions so as to endanger healthy tissues. To overcome this lack of efficacy in radiation therapy various means for administering oxygen to hypoxic tumors has been described in the prior art.
R. A. Lustig and N. L. McIntosh in Transfusion Medicine: Recent Technological Advances, page 29 through 38, 1986 demonstrated the use of Fluosol-DA to enhance the effect of radiation on animal tumors. They require 100% oxygen be given the animal through respiration for 72 hours after receiving 8-16 ml/kg of Fluosol-DA administered intravenously. The treated animals are then subjected to photon radiation after the intravenous injection.
S. Rockwell in International Journal of Radiation Oncology, Biology and Physics volume 11, pages 97 through 103. 1985 demonstrated the use of Fluosol-DA to improve oxygenation in solid tumors. The Fluosol-DA was injected intravenously into animals at the rate of 15 ml/kg. The author found that the presence of the fluorochemical did enhance the effect of radiation therapy.
J. M. Brown, et al. in Cancer Treatment Symposia, volume 1page 85, 1984 proposed the use of fluorochemical emulsions to enhance the effect of radio therapy for tumor treatment. No work accompanied the proposal to demonstrate the overall effect of such a proposal.
C. W. Song. et al. in International Journal of Radiation Oncology. Biology and Physics, volume 11. pages 1833 to 1836. 1985 demonstrated the increased radio sensitivity of tumors using perfluorochemicals as an intravenous injection into animals which were simultaneously breathing a carbogen atmosphere.
J. M. Yuhas. et al. in International Patent Application No. W084/00686 filed Mar. 1, 1984 teaches the use of a fluorochemical as diagnostic and oxygen carrier agents in the examination or treatment, respectively, of hypoxic tumors or as an intravenous adjuvant with an added drug or agent. The patent mentions intramuscular administration or injection at or near the site of hypoxia but teaches away from this by reciting that "direct contact" is ideal but "may not be achievable and in fact is not required."
Sara Rockwell, Timothy P. Mate, Caroline G. Irvin, and Mary Ann Nieremburg report in International Journal of Radiation Oncology. Biology, and Physics, volume 12, pages 1315 to 1318, 1986 the treatment of mice with a Fluosol-DA emulsion to heighten favorable response of radiation therapy on mammary tumors. The test mice did not show favorable enhancement when breathing air or nitrogen or when breathing carbogen alone without Fluosol emulsion injected intravenously. Only when Fluosol emulsion was injected intravenously while the mice breathed a carbogen-containing atmosphere did enhanced radio therapy efficacy become observed.
N. L. McIntosh in published European Patent Application No. 0201275 of Nov. 12, 1986 discloses a therapy of cancerous tumors by injecting multiple doses of perfluorocarbon emulsion into a patient and simultaneously having the patient breathe an oxygen-enriched atmosphere. In light of the oxygen-enriched breathing the McIntosh therapy necessarily involves vascular circulation of the emulsion to the lungs. Radiation or chemotherapy is then administered to the patient after the emulsion has carried oxygen from the lungs to the vicinity of the tumor. The emulsion is administered in an amount of from 2 to 15 ml per kg of body weight, preferably 4-10 ml/kg.
All of the above described procedures utilize injections that require circulation through the lungs or vascular system in order to carry oxygen to the tumor and therefore to enhance radiation therapy effects.